Something error when use com.typesafe.config API convert conf file to scala bean class

[dragonpic1988]

version 1.4.0
Did I make a mistake？
What is the correct way to do this？
scala code:
object AppMain {
def main(args: Array[String]): Unit = {
val conf = ConfigFactory.parseFile(new File("./center/app.conf"))
val app = ConfigBeanFactory.create(conf, classOf[App])
println("hello=" + app)
}
}

case class App(
config: Config
) {
def run(): Unit = {
println(config.run())
}
}

case class Config(
url: String,
safe: Boolean,
count: Int,
users: List[String]
) {
def run(): Unit = {
println("url=" + url)
println("safe=" + safe)
println("count=" + count)
println("users=" + users)
}
}
then, error:
Exception in thread "main" java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.intellij.rt.execution.CommandLineWrapper.main(CommandLineWrapper.java:64)
Caused by: com.typesafe.config.ConfigException$BadBean: com.saic.autobot.App needs a public no-args constructor to be used as a bean
at com.typesafe.config.impl.ConfigBeanImpl.createInternal(ConfigBeanImpl.java:129)
at com.typesafe.config.ConfigBeanFactory.create(ConfigBeanFactory.java:47)
at com.saic.autobot.AppMain$.main(AppMain.scala:13)
at com.saic.autobot.AppMain.main(AppMain.scala)
... 5 more
Caused by: java.lang.InstantiationException: com.saic.autobot.App
at java.lang.Class.newInstance(Class.java:427)
at com.typesafe.config.impl.ConfigBeanImpl.createInternal(ConfigBeanImpl.java:109)
... 8 more
Caused by: java.lang.NoSuchMethodException: com.saic.autobot.App.()
at java.lang.Class.getConstructor0(Class.java:3082)
at java.lang.Class.newInstance(Class.java:412)
... 9 more